1. Field of the Invention
The present invention relates to tape recorders. More specifically, the present invention is directed to a end-of-tape control system for tape recorders.
2. Description of the Prior Art
The need for sensing end-of-tape in tape recorders has long been recognized to prevent the tape from being fully unwound from a reel, and many prior art devices have been developed to accomplish this function. The earliest devices used a "feeler" arm to detect the amount of tape remaining on a reel, e.g., U.S. Pat. No. 3,609,777. The use of such mechanical arms, however, was not always satisfactory inasmuch as damage to the tape often resulted, and the arm presented mechanical problems in operating the tape transport. Later developments were directed to the use of optical sensors, e.g., U.S. Pat. No. 3,249,758. Such optical sensors, however, exhibited a new set of problems which included sensitivity to an ambient light, higher expense and unstable control over long periods of time. A recent development has resulted in a end-of-tape sensor system for detecting end-of-tape without the use of mechanical or optical devices, e.g., U.S. Pat. No. 3,849,661. However, such a prior art control system is not directly applicable to multi-speed tape transport systems for stopping the tape at the same point regardless of the selected tape speed and uses a complicated control system which introduces additional problems of instability and reliability. Accordingly, it is desirable to provide an end-of-tape sensor for tape transports which overcomes the aforesaid objections to the prior art devices.